Building a MRJAR with Gradle

WARNING: Before doing this, we strongly recommend to read this blog post which highlights the consequences of your decision.

Cross-compilation

Run ./gradlew run and Gradle will:

• compile classes from src/main/java with a Java 8 compiler
• compile classes from src/main/java11 with a Java 11 compiler

It will automatically download the right JDKs for you if you don't have them.

There's a dependency between the Java 11 classes and the Java 8 classes too, showing that it's not an issue.